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  • 1
    Electronic Resource
    Electronic Resource
    Importance of foraminifera for the formation and maintenance of a coral sand cay: Green Island, Australia (2000)
    Springer
    Coral reefs 19 (2000), S. 51-58 
    Details
    ISSN: 1432-0975
    Keywords: Key words Coral sand cay ; Foraminifera ; Sea level ; The Great Barrier Reef
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  CaCO3 production by reef-building organisms on Green Island Reef in the Great Barrier Reef of Australia is estimated and compared with the contribution of benthic foraminifera to the sediment mass of the vegetated sand cay. Major constituents of the cay are benthic foraminifera (mainly Amphistegina lessonii, Baculogypsina sphaerulata, and Calcarina hispida), calcareous algae (Halimeda and coralline algae), hermatypic corals, and molluscs. Among these reef-building organisms, benthic foraminifera are the single most important contributor to the sediment mass of the island (ca. 30% of total sediments), although their production of CaCO3 is smaller than other reef-building organisms. Water current measurements and sediment traps indicate that the velocity of the current around Green Island is suitable for transportation and deposition of foraminiferal tests. Abundant foraminifera presently live in association with algal turf on the shallow exposed reef flat, whose tests were accumulated by waves resulting in the formation and maintenance of the coral sand cay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003380050226
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Production of Metallogenium-like particles by heterotrophic manganese-oxidizing bacteria collected from a lake (1992)
    Springer
    Archives of microbiology 158 (1992), S. 100-106 
    Details
    ISSN: 1432-072X
    Keywords: Metallogenium ; Manganese-oxidizing bacteria ; pH dependence ; Bicarbonate ; Electron acceptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As a model of chemically stratified structure of environment typical to the chemocline of lakes, a semisolid gradient medium was prepared to cultivate heterotrophic manganese-oxidizing bacteria originally collected from a lake. The bacteria growing under the conditions described produced extracellularly Metallogenium-like particles similar to those which are often detected in the chemocline of lakes. This suggested that the naturally occurring Metallogenium-like particles originated in activities of such heterotrophic manganese-oxidizing bacteria. The manganese oxidation activity usually appeared only at the stationary phase of bacterial growth. The oxidation of Mn2+ and the formation of Metallogenium-like particles by the bacteria were observed at neutral or slightly acidic pH. not under alkaline conditions, which is a conspicuous difference from the inorganic oxidation of Mn2+ by O2. Bacterial manganese oxidation was stimulated by bicarbonate (50 or 500 μM). An experiment of addition of H2O2 to the incubation tubes isolated from atmosphere failed to confirm the availability of externally added H2O2 as the electron acceptor, suggesting that the bacterial manganese oxidation required the presence of O2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245212
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  • 3
    Electronic Resource
    Electronic Resource
    A unified analytical treatment of the acid-dissociation equilibria of weakly acidic linear polyelectrolytes and the conjugate acids of weakly basic linear polyelectrolytes (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 938-945 
    Details
    ISSN: 1435-1536
    Keywords: Key words Donnan model ; ion-exchange ; polyacrylic acid ; poly(N-vinylimidazole) ; acid-dissociation equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The influence of added sodium chloride concentration levels on the acid-dissociation equilibria of a weakly acidic linear polyelectrolyte and a conjugate acid of weakly basic linear polyelectrolyte has been investigated potentiometrically by use of polyacrylic acid (PAA) and poly(N-vinylimidazole) (PVIm) as examples of polyelectrolytes. Both equilibria are strongly influenced by the degree of dissociation of the polyacids as well as the concentration levels of sodium chloride due to an electrostatic effect originating from the negatively or positively charged polymer surfaces. These have been analyzed in a unified manner by taking accounts of two-phase properties of the charged linear polyions. Distribution of counterions and coions between a polyelectrolyte phase formed around the polymer skeleton and a bulk solution phase has been rationalized by a Donnan’s relation. Introduction of a volume term for the polyelectrolyte phase permits definition of averaged concentrations of mobile ions in the vicinity of the polyion molecules, which enables us to define hypothetical intrinsic acid-dissociation constants in the polyion domain. The intrinsic constants estimated by extrapolation of apparent acid-dissociation constants at zero-charge state are in good agreement with the acid-dissociation constants of the monomer analogs of the polymers, i.e., acetic acid for PAA and imidazole for PVIm, respectively. The difference between the apparent and intrinsic acid-dissociation constants for PVIm was much higher than that for PAA at defined degree of dissociation of the polyacids, even though the separations of the functionalities fixed on the linear polymers are approximately equal to each other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050169
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  • 4
    Electronic Resource
    Electronic Resource
    Evaluation of the Donnan model for polyelectrolytes using the composite Poisson-Boltzmann equations (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 803-811 
    Details
    ISSN: 1435-1536
    Keywords: Donnan model ; Donnan potential ; polyelectrolyte ; counterion binding ; potential distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The validity of the macroscopic Donnan model for polyelectrolytes in an electrolyte solution is examined by taking into account the effects of the varying potential distribution across the boundary between a polyelectrolyte and the surrounding solution, using the composite Poisson-Boltzmann equations for the polyelectrolyte interior and the surrounding solution. Calculations are made for a planar polyelectrolyte of thickness 2d and a planar polyelectrolyte layer of thicknessd covering a rigid surface, both showing the identical potential distribution. A simple expression for a correction factor for these effects is derived which enables to evaluate various corrected quantities in the polyelectrolyte interior such as the average potential, the average ionic concentration, the average degree of dissociation and the apparent dissociation constant of ionizable groups in the polyelectrolyte. It is found that when κd≪1 (where κ indicates the Debye-Hückel parameter) the macroscopic Donnan model can safely be applied, while as κd decreases the effects of the varying potential distribution become appreciable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652421
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  • 5
    Electronic Resource
    Electronic Resource
    Interaction of a cationic surfactant to sodium polyphosphates with different degrees of polymerization (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 40-45 
    Details
    ISSN: 1435-1536
    Keywords: Key words Polyphosphate ; degree of polymerization ; electrostatic potential ; surfactant ; binding isotherm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The binding behavior of dodecylpyridinium chloride to sodium polyphosphate of various degrees of polymerization (DP) was studied by means of a potentiometric titration method using a surfactant-selective electrode in the presence of 10 mM NaCl at 30 °C. Binding isotherms were analyzed by direct calculation of a matrix expressing the partition function. It is found that binding affinity depends prominently on the polymer chainlength when the DP value is less than ca. 35, but becomes nearly independent on DP thereafter. No binding was observed for linear triphosphate or cyclic trimetaphosphate anions. The picture that arises for the binding is that the polymer’s end-effect reduces the apparent cooperativity, while the hydrophobic interaction with neighboring surfactant remains constant because of the short-range nature of the interaction. The so-called end-effect is associated with a superimposition of electrostatic potentials around the polymer rods. Both the matrix method and the Satake–Yang equation were carried out for simulations, and the matrix one shows a better fitting with the experimental data for the short-chain polyelectrolyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050206
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  • 6
    Electronic Resource
    Electronic Resource
    A calorimetric study of the acid dissociation of the conjugate acids of poly(N-vinylimidazole) and polyallylamine (2000)
    Springer
    Colloid & polymer science 278 (2000), S. 1-7 
    Details
    ISSN: 1435-1536
    Keywords: Key words Poly(N-vinylimidazole) ; Polyallylamine ; Acid-dissociation equilibria ; Calorimetric titration ; 35Cl nuclear magnetic resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thermodynamic parameters for acid dissociation of the conjugate acids of poly(N-vinylimidazole) and polyallylamine have been determined in the presence of sodium chloride and sodium nitrate. Even though the plots of ΔG 0 against the degree of dissociation, α, are highly dependent on the added salt concentration levels, the concentration effect has never been observed for the corresponding ΔH 0 versus α plots. The effect on the ΔG 0 versus α plots has been attributed to the entropy change of the counterions between a polyelectrolyte phase and a bulk solution phase. The α dependency of ΔH 0 is affected remarkably by the kinds of cationic polymers and counter-anions. Each ΔH 0 value at completely neutralized conditions is quite close to the corresponding ΔH 0 value of the monomer analog. The difference in the ΔH 0 values at fully charged conditions has been explained by the heats due to The ion-pair formation of chloride anion to the conjugate acids of poly(N-vinylimidazole) and polyallylamine has been supported by 35Cl NMR measurement. It has also been suggested that chloride anions bind the basic polymer molecules even at fully neutralized conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050001
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  • 7
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    Heterogeneous dissolved organic nitrogen supply over a coral reef: first evidence from nitrogen stable isotope ratios (2013)
    Springer
    In:  Coral Reefs, 32 (4). pp. 1103-1110.
    Details
    Publication Date: 2016-09-22
    Description: Dissolved organic nitrogen (DON) potentially plays a major role in sustaining the high productivity and biological diversity of coral reefs. However, data are scarce regarding sources and sinks of DON. This study, for the first time, determined the N-15 isotopic composition of total dissolved nitrogen (delta N-15(TDN)), reflecting the isotopic signature of DON, in the water column over a coral reef. The uniformity in delta N-15(TDN) during high tide (3.2 +/- A 0.3 aEuro degrees) indicated that the DON was mainly derived from offshore waters. In contrast, higher spatial heterogeneity of delta N-15(TDN) (3.1 +/- A 0.9 aEuro degrees) and DON concentrations during low tide indicated the existence of local DON sources patchily distributed over the reef. Low delta N-15(TDN) values located mid-reef were indicative of DON release from organisms that obtained their N via N-2 fixation, whereas high delta N-15(TDN) appeared to reflect localized release of DON by organisms exposed to dissolved inorganic nitrogen with elevated N-15, such as from terrestrial and offshore inputs. Collectively, the results highlight the importance of spatial patterns in DON release from reef communities in the N cycling of coral reefs.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00338-013-1070-9
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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